Compliant coupling system for adapting sonic well drill apparatus to jarring function



June 1 6, 1959 ODINE 2,890,757

A.G.B COMPLIANT COUPLING SYSTEM FOR ADAPTING SONIC WELL DRILL APPARATUSTO JARRING FUNCTION Filed 001;. 28, 1957 FIG. 3 FIG. 4 FIG. 1 26 FIG. 2/2 $24 26- 20 A A 23 22 PK H /2| A 4 24 2s 2O ALBERT cs. BODINE ATTORNEYboMPLIANT COUPLING SYSTEM FOR ADAPTING SONIC WELL DRILL APPARATUS TJARRING FUNCTION Albert G. Bodine, Sherman Oaks, Calif. Application0ctober'28, 1957, Serial No. 692,787

1 Claim. (Cl. 166-177) This invention comprises a compliant couplingsystem adapted to be located between a vibratory rod assembly normallycomprising the motivating means for a sonic vibratory well drill bit anda grapple of the type used in oil well jars, whereby the sonic vibratorydrill assembly may be used to perform the function of fishing or jarringloose any drill pipe or other dn'll tools which have become stuck in anyhole or well in the earth, irrespective of the type of drillingoperation resulting in the pipe or tool being stuck.

Anobject of the invention is accordingly to provide a simple means bywhich a sonic drill may be adapted to the purpose of occasional jarringoperations.

A suitable sonic drill of the type contemplated by the invention isdisclosed in my Patent No. 2,554,005, May 22, 1 951, and said patent isincorporated herein by reference, and the details thereof will not,therefore, require to be shown here. Such a drill, when in the field,has occasional unique usefulness, by a simple conversion", as a servicetool in particular situations where pipe or tools have become stuck in awell. Such a drill comprises, essentially a massive longitudinallyvibratory elastic rod string, usually a string of drill collars, avibration generator for setting up the vibrations in the rod string, amotor for driving the vibration generator, and a bit screwed to thelower end of the rod string. The conversion of the present inventionconsists in replacing the bit by a coupling extension comprising acompliant string of light pipe, e.g., drill pipe, of a preferred lengthof approximately one quarter wave length. With respect to wave length,as disclosed in my aforesaid patent, the rod string may vibrate in ahalf-wave length standing wave mode, with a velocity antinode at eachend, and a stress antinode at the mid-point. The coupling extensionpipe, for this case, may then be half the length of the half wave lengthrod string. The lower end of the compliant coupling extension carries ameans for grasping a fish, such as an overshot or spear.

In operation, the sonic drill vibration generator is caused to resonatethe drill rod assembly in exactly the same manner as when driving thesonic drill bit. In this case, however, the sonic wave action is appliedto the top end of the above-described compliant coupling pipe. The lowerend of this compliant pipe will be understood to be coupled tightly tothe upper end of the fish, which is stuck fast in the well hole. Thecompliant pipe accordingly becomes an acoustic lever, having a largecyclic elastic displacement amplitude where coupled to the vibratingdrill rod string, and minimized displacement amplitude at the overshotor spear, i.e., where coupled to the stuck fish. The first or upperregion is accordingly a point of relatively low impedance (low ratio ofcyclic force to displacement), while the lower region, at the fish, is arelatively high impedance region (high ratio of cyclic force todisplacement). High cyclic forces are thus applied to the fish" forloosening it from its stuck condition. The fish becomes a part of theacoustic circuit, and its contact surres Patent ice face at the stuckpoint in the well becomes a high impedance acoustic energy transmitter.By virtue of acoustic mismatch of impedance at the stuck interface,relative vibrations occur, with a resulting powerful loosening action.In addition, alternating waves of compression and tension, set up in thecoupling pipe as a result of the driving action of the drill rodassembly, are propagated down the coupling pipe, and cause a dilationalwave phenomenon in the fish, i.e., a sonic frequency fluctuation incircumference. Earthen structure cannot respond well at the sonicfrequencies here involved,which are of the order of to c.p.s., andliterally stand back dynamically from the stuck fish.

The invention will be further understood from the following detaileddescription of an illustrative embodiment thereof, reference for thispurpose being had to the accompanying drawings, in which:

Figure 1 is a view, partly in elevation and partly in section, showing atypical installation of surface equipment for a sonic drill, andincluding the main portion of the drilling assembly proper;

Figure 2 is a view showing a portion of the sonic drilling assemblyextending downward from the parts shown in Figure l;v

Figure 3 is a view showing the balance of the drilling assembly, andunderstood to extend downwardly from the parts shown in Figure 2, Figure3 showing also the jarring accessory of the present invention; and

Figure 4 is a view, partly in elevation and partly in section, showingthe jarring accessory of the present invention to larger scale, with anintermediate portion broken away, and showing the application of theaccessory to a fish.

At the ground surface (Fig. 1) is a conventional derrick 10, draw works11 driving rotary table 12, kelly 13, extending through table 12, swivel14 coupled to the upper end of kelly 13, and hook 15 supporting the barof swivel 14. Hook 15' is supported from above in the conventionalmanner. Mud fluid such as is conventionally used in rotary oil welldrilling is delivered from con ventional equipment to pipe 16 and thencehose 17 to swivel 14, from which it flows down through kelly 13 to thedrill pipe string 18. The pipe string 18 will be understood to be madeup of a number of usual drill pipe lengths coupled together by usualtool joints such as indicated at 19.

The drilling assembly proper comprises, starting from the top, anelastic vibration generator assembly G including a motor unit 20, drivenby the mud fluid circulated through the system, a mechanical vibrator21, driven by said motor unit, and adapted to generate cyclic,vertically-directed force pulses, and a long interconnecting part 22.This vibration generator assembly is supported from drill string 18 bymeans of a relatively long and heavy sub 23 composed typically of asection of drill collar, together with a relatively short length ofthinner walled pipe or casing 24. The drilling assembly proper furthercomprises an elongated elastic longitudinally vibratory rod 25, of verysubstantial mass and length, in this instance made up of threeconventional collars 26 connected end to end by subs 27, this assemblyof drill collars being coupled to the lower end of vibrator 21 by meansof sub 28.

A sonic drill of the. type contemplated is completed by means of a bit(not here shown) coupled to the lower end of the lowermost of the drillcollars 26, all as set forth in my said Patent #2,554-,005. The detailsof the component parts of such a sonic drill are fully set forth in theaforesaid patent and need not be repeated herein. Suifice it to say thatin the operation of the sonic drill, the vibration generator assembly Gcauses cyclic vibration forces to be applied to the upper end of thedrill rod or collar 25 at the frequency of a longitudinal resonantelastic vibration of said rod. Typically, the frequency is such as tocause the rod 25 to vibrate as a free-free bar in substantially a halfwave length longitudinal standing wave mode, though the bar may also beoperated in a full wave length mode or other modes, as set forth in mysaid earlier patent. The bit impacts against the foimation as a resultof the vibration of the rod 25.

According to the present invention, in course of field operations withthe sonic drill, upon encountering an occasional situation in which atool or fish is lost and stuck in the well, the sonic drill isconverted, by means of a simple accessory, to the function of grapplingthe fish and hence jarring it loose from its stuck condition. To thisend, the sonic drill bit, not here shown, is uncoupled from the lowerend of the rod string 25 made up of collars 26, and replaced by acompliant pipe 30, which may be a section of common drill pipe. The pipe30 has a threaded coupling pin 31 at the top adapted to be screwed in tothe threaded box 32 at the lower end of the lowermost collar 26. At itslower end, pipe 30 has a threaded coupling pin 33 threaded into the box34 at the top of a somewhat diagrammatically shown grappling tool 35,which may be either an overshot, or spear, of any character desired, butis here shown in the form of an overshot embodying a tubular body havingwedge slips 36 designed for engagement with the fish 37. As will beunderstood, the string of tools, with the pipe 30 and grappling tool 35in place, is manipulated to seize the fish 37; and a tension may then betaken in the string of tools to assure that the fish is firmly held bythe wedge slips.

Preferably, the pipe 30 is given a length approximately one quarter wavelength of the wave pattern generated in the longitudinally vibratory rodstring 25. Thus, if the rod string 25 receives force impulses at suchfrequency for its length as to vibrate in a half wave length (M 2)standing wave mode, as indicated in Figure 3, then the coupling pipe 30may have a. length approximately equal to a quarter wave length (M4).The result, as diagrammed in Figure 3, is that the rod string 25, thecoupling pipe 30, the grapple 35, and the fish 37 down to the stuckpoint, are all included in the acoustic circuit, and experience asubstantially three-quarter wave length standing wave of the characterrepresented at s when the apparatus is in operation.

Operation is as follows: The vibration generator, as in drilling,applies cyclic vibration forcesto the upper end of the drill rod 25 at aresonant frequency of the rod, causing a half wave length standing wavein the rod, as indicated in Figure 3. The lower end of the rod 25vibrates against the upper end of the compliant coupling pipe 30. At thecoupling point between heavy rod 25 and compliant coupling pipe 30,there exists a velocity antinode V, which is a region of relatively lowimpedance, characterized by a relatively low ratio of cyclic force todisplacement amplitude. At the lower end of the coupling pipe 30, theacoustic system is held relatively firm by the rigid coupling to thefish, and stuck condition of the fish in the well bore. Here,accordingly, there exists a stress antinode region P, characterized by arelatively high ratio of cyclic force to displacement amplitude. Thecompliant coupling pipe 30 thus acts like an acoustic lever translatingthe relatively low cyclic force and high displacement amplitude at thecoupling point between rod 25 and pipe 30 into relatively high cyclicforce and low displacement amplitude at the grappling tool, and at thestuck point between the fish and the well bore. The fish becomes a partof the acoustic circuit, and transmits acoustic energy into the walls ofthe well bore. By virtue of the acoustic mismatch of impedance at thepoint of contact between the fish and the well bore, relative vibrationsoccur, which loosen the fish from the bore. Also, the alternating wavesof compression and tension set up in the coupling pipe cause alternatingdilations and contractions of the fish at sonic frequency and since theearths structure is incapable of following these closely, a furtherpowerful loosening factor is introduced. The fish may be progressivelyloosened from the well bore in the downward direction; and in such case,the standing wave pattern along the coupling pipe 30 and fish, down tothe stuck point, may progressively lengthen. This may have a tendency tolower the resonant frequency of the overall'system, and may cause adownward shift of the node N. But .because of the much heavier crosssection of the rod as compared to the coupling pipe 30, this effect issmall, and the standing wave pattern from the upper end of pipe to thestuck point can lengthen considerably without greatly influencing theportion of the standing wave pattern along the rod 25, or the overallresonant frequency.

The accessory provided by the invention thus enables a sonic drill ofthe character described to be employed occasionally to carry out easilyand inexpensively a fishing and jarring problem encountered in thefield.

I claim:

An apparatus for jarring and retrieving a fish which has become stuck ina well hole in the earth, comprising, in combination with a sonic earthboring apparatus that includes a string of drill collars having a bitcoupling means at the lower end thereof, and a vibrator and drive motortherefor coupled to said string of drill collars for applyingcyclic'longitudinal forces thereto at a resonant frequencythereof for amode of longitudinal standing wave vibration, whereby a longitudinalstanding wave is set up in said string of collars, and a velocityantinode of said standing wave appears at the lower end thereof: anelastically compliant coupler pipe having a coupling at its upper endfor coupling to said bit coupling means at the lower end of said stringof collars, said elastically compliant coupler pipe having a lengthapproximately equal to a quarter wave length of said standing wave setup in said string of drill collars, and a grapple on the lower end ofsaid quarter wave length compliant coupler pipe adapted for grapplingand tightly engaging a fish which has become lost in a well bore, all insuch manner that said longitudinal standing wave continues on down saidcoupler pipe, and said coupler pipe vibrates in sul'r stantially aquarter-wavelength standing wave mode, with a velocity antinode at itsupper end, and a stress antinode in the general region of the grapple onits lower end in engagement with the fish," whereby the fish is vibratedwith a high ratio of cyclic force to displacement amplitude as comparedto a low ratio of cyclic force to displacement amplitude in theapparatus in the region of the coupling between the string of drillcollars and said coupler pipe.

References Cited in the file of this patent UNITED STATES PATENTS

